Index: wp-includes/option.php
===================================================================
--- wp-includes/option.php	(revision 20782)
+++ wp-includes/option.php	(working copy)
@@ -44,6 +44,8 @@
 	if ( defined( 'WP_SETUP_CONFIG' ) )
 		return false;
 
+	$default = apply_filters( 'default_option_' . $option, $default );
+
 	if ( ! defined( 'WP_INSTALLING' ) ) {
 		// prevent non-existent options from triggering multiple queries
 		$notoptions = wp_cache_get( 'notoptions', 'options' );
@@ -754,6 +756,8 @@
  	if ( false !== $pre )
  		return $pre;
 
+	$default = apply_filters( 'default_site_option_' . $option, $default );
+
 	if ( !is_multisite() ) {
 		$value = get_option($option, $default);
 	} else {
Index: wp-includes/class-wp-customize-setting.php
===================================================================
--- wp-includes/class-wp-customize-setting.php	(revision 20782)
+++ wp-includes/class-wp-customize-setting.php	(working copy)
@@ -68,8 +68,10 @@
 			case 'option' :
 				if ( empty( $this->id_data[ 'keys' ] ) )
 					add_filter( 'pre_option_' . $this->id_data[ 'base' ], array( $this, '_preview_filter' ) );
-				else
+				else {
 					add_filter( 'option_' . $this->id_data[ 'base' ], array( $this, '_preview_filter' ) );
+					add_filter( 'default_option_' . $this->id_data[ 'base' ], array( $this, '_preview_filter' ) );
+				}
 				break;
 			default :
 				do_action( 'customize_preview_' . $this->id );